Red Bull advisor Helmut Marko has said he doesn't feel Mark Webber will be to challenge for an F1 championship, despite being more than capable of fighting for race victories.

Webber has driven for the team since 2007, taking nine wins and a best finish of third in the standings in both 2010 and 2011. By contrast, team-mate Vettel has won 25 times and taken three championship titles since being promoted from the Toro Rosso team in 2009.

With that in mind, Marko said he doubted if Webber would be able to challenge for a title himself, arguing that the Australian could have found it psychologically difficult to deal with the way in which Vettel had come in and made his mark on the team.

"For much of his career, Mark was never in a top team, but he was always regarded as a high flyer if he only could get into the right team," he was quoted as telling the Red Bulletin

"Then Red Bull puts him in a car - a possible winner - and suddenly along comes this young kid and he snatches the booty from under Mark's nose. Psychologically it's not easy, of course; this would gnaw away at anyone's confidence. It's more than understandable."

Marko added that he felt Webber struggled to deal with the pressure of trying to put together a title bid even though he could have races where he is 'unbeatable'.

"It seems to me that Webber has on average two races per year where he is unbeatable, but he can't maintain this form throughout the year," he said, "and as soon as his prospects start to look good in the world championship, he has a little trouble with the pressure that this creates.

"In comparison with Seb's rising form, it seems to me that Mark's form somehow flattens out. Then, if some technical mishap occurs, like with the alternator for example, he falls relatively easily into a downward spiral.

"No driver remains unaffected by this, because the tension is palpable. In 2010, it was particularly extreme."